Magnetic actuation makes use of “Lorentz Forces” in which a force on a current-carrying conductor is related to the current in the conductor and the strength of a magnetic field across the conductor. The force exerted is perpendicular to the direction of the current in the conductor and perpendicular to the magnetic field.
In magnetically actuated systems, power efficiency can be gained by using larger magnets to create a stronger magnetic field. The larger magnets, however, are heavier and increase volume requirements of the resulting system. On the other hand, volume and weight can be reduced by increasing the current in the conductor, but this is at the expense of increased power consumption. Accordingly, one can see that a trade-off exists between power consumption and weight/volume in magnetically actuated systems.
It is desirable to reduce both power consumption and weight/volume in magnetically actuated systems.